Three way flow regulating valves

ABSTRACT

A flow regulating valve comprises a control piston arranged to be impinged on both ends by a flow and further piston means, connected with the piston and arranged to be acted upon by the flow substantially statically so that the force on the second piston substantially represents the static flow pressure.

United States Patent 1191 Teubler et al. July 10, 1973 154] THREE WAYFLOW REGULATING VALVES [56] References Cited v [75] inventors: HeinzTeubler, Bad Homburg; Otto UNITED STATES PATENTS Laflgmh, Usingen bothofGerflmlfly 3,532,104 *10/1970 Hoen 137 117 x 2,980,173 4/1961 Perkey137/117 [73] Assgnee' GmbH H 3,323,533 6/1967 Reimer 137/118 x [22]Filed: NOV. 1, 1971 3,334,705 8/1967 Lam 137/118 X [21] A l N 194 5953,385,311 5/1968 Allen 137/101 Related US. Application Data PrimaryExaminer-Robert G; Nilson [63] Continuation of Ser. No. 4,719, Jan. 21,1970, Attorney-Arthur Ralsch, John Klsselle et abandoned.

' o [57] ABSTRACT [30] Foreign Apphcauon Pnomy Data A flow regulatingvalve comprises a control piston ar- Jan. 23, 1969 Germany P 19 03 305.7ranged to be impinged on both ends by a flow and ther piston means,connected with the piston and ar- [52] US. Cl. 137/117, 137/101 rangedto be acted upon by the flow substantially stab CL .th t th force onsecond pi t b p [58] Fleld of Search 137/100, 101, 116.3, tianyrepresents the static flow pressure 1 Claim, 2 Drawing Figures THREE WAYFLOW REGULATING VALVES This is a continuation of U.S. Pat. applicationSer. No. 4,719, filed Jan. 21, 1970, now abandoned.

The present invention relates to three way flow regulating valves andmore particularly to such valves of the type comprising a valve plungeror piston, whose one first side is impinged on by a main flow to beregulated and on an opposite second side is acted upon by a branch flowcoming from the inlet chamber.

Such three way flow regulating valves, which for example are mounted inthe cover of a liquid pump, can be used to ensure that when the speed ofdrive, and consequently the output flow of the pump change, a varyingbranch flow is split off in such a manner that a substantially constantmain flow is provided. In the case of a previously proposed three wayflow regulating valve of the above-mentioned type the action of thesplit off branch flow on the valve piston or plunger could not produce asufficiently constant main flow owing to hydrodynamic effects.

One object of the invention is to overcome this shortcoming.

In accordance with one aspect the present invention consists in a threeway flow regulating valve, comprising means defining an inlet chamber, avalve piston, the valve piston being arragned to be' acted upon on afirst side by a main flow to be regulated, while an opposite second sideof the piston is acted by a branch flow leaving the inlet chamber, andmeans defining an additional direct connection for transferring thestatic pressure of the inlet chamber to the last-mentioned second sideof the piston. In this respect the invention takes account of the factthat in the case of a varying pumped flow the branch also variescorrespondingly and therefore in acting upon the valve piston in knownconstructions produces spurious effects, which are attributable tochanging pressure relationships.

In order to ensure satisfactory operation of the static pressureobtaining in the inlet chamber on the valve piston or plunger, theinvention makes the further proposal that for transmitting the fullstatic pressure a connecting duct should extend between the inletchamber and a region, separated from the branch flow, on the second sideof the piston, no or only a slight, insignificant flow obtaining in thisconnecting duct.

Preferably this measure is provided by arranging for corss-sectionalcontrol of a main flow opening on the first side of the piston.

The invention is now described with reference to an embodiment as shownin the attacheddrawing.

I with the advantage in the cover of a liquid pump, in

order to ensure that, despite variation in the driving speed, the pumpdelivers the main flow Q, at a substantially constant rate.

In the inlet chamber 1 the pump output flow Q assumes a static pressurewhich depends on the load at a valve land to separate the second side ofthe piston,

on which the branch flow acts, from the region in which the connectingduct opens.

In accordance with afurther advantageous featureof the invention afurther improvement or effect of or on the regulating characteristic ofthe valve can be obtained by making the connecting duct in the form of aslot whose outlet port is controlled by the valve land in order toinfluence the regulating characteristic of the valve, dependent on theposition of the valve piston.

A further development of the invention bringing about an effect on orimprovement in optimum regulating characteristics and optimum dynamicbehavior resides in that the valve land has a passage joining the tworegions on the second side of the piston and cooperating with theconnected duct.

A further improvement in the regulating characteristic of the valve isachieved by the invention in that the additional connecting duct betweenthe inlet chamber and the second side of the piston is matched with thethe connection for the main flow Q, or the load at the branch flow Q Themain flow Q passes from the inlet chamber 1 to an outlet duct or passage2 via a chokelike connecting hole 3 and an intermediate chamber 4,

from which the outlet passage 2 extends. The intermediate chamber 4 islimited on one side by a valve piston or plunger 5 so that the left-hand(or first) side of the piston is impinged upon by the main flow Q,flowing through the intermediate chamber 4. In the intermediate chamber4 a helical spring is arranged which urges the piston 5 to the right interms of FIG. 1. The outlet passage 2 is so arranged that its inlet port12 leading into the chamber 4 is changed in size by thefront part of thepiston 5 as the latter moves.

The branch flowQ (=Q,-Q,) leaves the inlet chamber 1 via the duct 14 andpasses into achamber 11 on the rear (or second) side of the valvepistons and from this position via a choke opening 6, controlled by thispiston 5, to the outlet 7 for the branch flow Q Owing to thecross-sectional relationships the flow velocity of the branch flow 0; inthe chamber 11 is above that in the inlet chamber 1, so tha theeffective pressure which in the chamber 11 acts on the rear or secondside of the piston 5 is reduced and thus is not capable, with the partsof the arrangement so far specifically described of providing thedesired regulation of the output or main How 0,. In order to transmitthe static pressure in the inlet chamber 1 to the rear of second side ofthe valve' plunger or piston 5, an additional connecting duct 8 isprovided. This connecting duct transfers the static pressure in theinlet chamber 1 to a chamber 9 which is separate from the chamber 11through which the branch flow Q, passes, no or only a slight flowmovement occurring in the connecting duct 8. In order to separate thechambers 9 and 11 on the second or rear side of the piston 5 a land 13is provided on an extension of the piston 5.'This land cooperates withthe bore of the hole in which the piston slides in forming the separatechambers 9 and II.

The piston land 13 (which can be considered to form a further piston)and the connecting duct 8 may be preferably so arranged in relation toeach other that the port at the outlet end of the connecting duct 8 iscontrolled by the valve land 13. This leads to an effect on theregulation characteristic of the valve in accordance with the positionof the valve piston 5. Furthermore the land 13 is provided with apassage 10 which connects the chambers 9 and l 1 so that owing to thecooperation with the connecting duct 8 in the case of only a slight flowoptimum features are achieved as regards the regulation characteristicand dynamic behavior. For this purpose the connecting duct 8 and/or thepassage 10 in the land 13 can be matched to suit the choke 3 in the mainflow Q This is achieved by providing an extension or shoulder, notshown, on the front side of the valve piston 5 which controls the freecross-section of the connecting hole 3. ln additions a pressure limitingvalve 15 can be provided which can be of entirely conventionalconstruction and is therefore not described in any detail.

Referring to FIG. 1, pressure is sensed in cavities 4, 11 and 9. Flowinto cavity 4 is restricted by the controlled flow orifice 3. No flowwill go out the secondary port until pump delivery exceeds what can beput through orifice 3. The spring offset on the spool accomplishes this.

When pump delivery is increased, pressure builds up in cavities 11 and 9because of the resistance to flow through orifice 3. This causes thespool to shift toward cavity 4. The amount of spool shift isproportional to the pressure differential between cavities 4 and 9.

Flow from the primary port is held to an almost constant volume, asdetermined by orifice 3, and the metering action of the spool at thearea of the left of spool 5. Flow to the secondary port varies with pumpdelivery. All flow not going out the primary port is diverted to thesecondary port through the metering area past land 6.

FIG. 2 shows the relationship between the pump output flow Q and theregulated main or out flow 0,. While Q denotes the main flow, previouslyfound to be unsatisfactory, of the three way flow regulating valvewithout the duct 8 and the land 13, the course of Q indicates that thefeature of the invention a substantially constant regulated main currentor flow O is available despite an increase in the magnitude of thepumped flow using the land 13 and the duct 8. Furthermore the matchingof the valve duct 8 to suit the passage 10 and additionally theconnecting hole 3-brings about a substantial effect on the regulaingcharacteristic of the three way flow regulating valve in order to beable to meet the most varied practical requirements.

We claim:

1. A three way flow regulating valve, comprising a housing, a pistonsliding in a hole in the housing, said housing having an inlet chamberto which an input flow is directed, first and second inlet duct meansassociated respectively with the first and second sides of the pistonfor splitting up the input flow in the inlet chamber into two flowsimpinging on opposite first and second sides of the piston,respectively, the flow on the first side passing to an output duct,while the flow on the second side passing out through a further outletduct, port means cooperating with the piston for enabling the piston toregulate the flow on its first side, means biasing the piston, saidsecond duct means from said inlet chamber to said second side of saidpiston having at least a portion of reduced cross section such that thevelocity of the fluid on the second side of the piston is increased andthe pressure of the fluid on said second side of the piston isdecreased, a land on the piston on the second side of the latter andcooperating with the hole in the housing in defining two chambers, thefirst chamber being between the land and the piston and having fluiddirected thereto by said second duct means, and the second chamber beingon the other side of said land, an additional duct in the housingextenda passage through it connecting the two chambers.

1. A three way flow regulating valve, comprising a housing, a pistonsliding in a hole in the housing, said housing having an inlet chamberto which an input flow is directed, first and second inlet duct meansassociated respectively with the first and second sides of the pistonfor splitting up the input flow in the inlet chamber into two flowsimpinging on opposite first and second sides of the piston,respectively, the flow on the first side passing to an output duct,while the flow on the second side passing out through a further outletduct, port means cooperating with the piston for enabling the piston toregulate the flow on its first side, means biasing the piston, saidsecond duct means from said inlet chamber to said second side of saidpiston having at least a portion of reduced cross section such that thevelocity of the fluid on the second side of the piston is increased andthe pressure of the fluid on said second side of the piston isdecreased, a land on the piston on the second side of the latter andcooperating with the hole in the housing in defining two chambers, thefirst chamber being between the land and the piston and having fluiddirected thereto by said second duct means, and the second chamber beingon the other side of said land, an additional duct in the housingextending from said inlet chamber to said second chamber and providingan additional direct fluid connection for the static pressure of theinlet chamber to the second side of the piston, said valve land beingprovided with a passage through it connecting the two chambers.